This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Analysis of promoter cis elements of ribosomal protein (RP) genes identified two common ribosomal protein promoter motifs called TRP1 and TRP2. Nuclear proteins that bound to these TRP elements were characterized using EMSA, and the motif responsible for protein binding to TRP2 within the promoter encoding small ribosomal protein 13 (rps13) was identified using linker scan mutagenesis. This motif, TGCATGA, is the same as the motif known to bind an Apetela-2 (AP-2) apicomplexan transcription factor, a member of a plant-like family of transcription factors present in apicomplexan parasites but not in animals. Structural modeling of AP-2s identified a critical motif for DNA binding. TRP element interactions with histone acetyltransferases, MYST-A and MYST-B were demonstrated by gel shift using &#8712;+/-MYST-A/B in EMSAs and ChIP studies. Thus, proteins likely to participate in key regulatory pathways determining tachyzoite growth and growth arrest were identified.